This invention is concerned with a process for the production of 1-[2-(phthalimidoethyl)]-6-substituted-4H-s-triazolo[4,3-a][1,4]benzodiaze pines, which are intermediates for the production of 1-(2-aminoethyl)-6-substituted-4H-s-triazolo[4,3-a][1,4]benzodiazepines.
The novel process and the products thus produced can be illustratively represented as follows: ##SPC2## wherein Ar is phenyl, o-chlorophenyl, o-fluorophenyl, or 2-pyridyl; and wherein the A ring is unsubstituted or substituted by fluoro, chloro, bromo, trifluoromethyl, or nitro.
Compound III is converted to 1-(2-aminoethyl)-6-phenyl-4H-s-triazolo[4,3-a][1,4]benzodiazepines IV and V by the following process: ##SPC3##
Wherein R is lower alkyl, such as methyl or ethyl; and Ar and ring A have the same significance as above.
The process III.fwdarw.IV.fwdarw.V has been disclosed in pending application Ser. No. 550,120, filed Feb. 14, 1975. It consists of treating a compound of formula III with hydrazine usually in a lower alcohol e.g. ethanol, propanol at reflux to obtain compound IV and treating if desired compound IV with a carboxylic acid aldehyde in the presence of reducing agent to yield compound V.
The process of this invention I.fwdarw.II.fwdarw.III, comprises: treating compound I with formaldehyde or paraformaldehyde in an inert organic solvent e.g. xylene, toluene, chlorobenzene or the like solution at temperatures between 100.degree.-140.degree. C. to give compound II. Compound II is treated with phthalimide and triphenylphosphine in an inert organic solvent, and the mixture is finally reacted with a lower dialkyl azodicarboxylate to give compound III.